Role of diabetes health literacy, psychological status, self-care behaviors, and life satisfaction in predicting quality of life in type 2 diabetes

One of the factors that can affect the quality of life is the psychological status of people. Also, the psychological status of individuals can be affected by other variables. Therefore, this study was aimed to determine the role of diabetes health literacy, psychological status, self-care behaviors, and life satisfaction in predicting the quality of life in Iranian patients with type 2 diabetes. This cross-sectional study was conducted in Iran in 2021 among 300 patients with type 2 diabetes. The method of selecting the participants in this study was the proportional stratified sampling method. Data collection instruments included six questionnaires of demographic questionnaire and diabetes status, DASS-21 questionnaire (depression, anxiety, and stress), diabetes health literacy scale, self-care behavior questionnaire, satisfaction with life scale (SWLS), and quality of life questionnaire. Statistical methods such as independent sample t test, one-way analysis of variance, linear regression test, and Pearson correlation were used to analyze the data. Based on the results of Pearson correlation test, there was a positive and significant correlation between diabetes health literacy (r = 0.438, p < 0.001), depression (r = − 0.380, p < 0.001), anxiety (r = − 0.355, p < 0.001), stress (r = − 0.423, p < 0.001), and SWLS (r = 0.265, p < 0.001) with quality of life. Based on the results of linear regression, variables of diabetes health literacy, life satisfaction, self -care behaviors, depression, stress, anxiety, age of onset of diabetes and diabetes duration were able to predict 31% of the quality of life (p < 0.001). The results of this study indicated that diabetes health literacy, life satisfaction, stress and the duration of diabetes are able to predict the quality of life of patients with diabetes. Therefore, it is necessary to pay more attention to these effective variables training programs, especially health literacy, the effect of which is very obvious in this study.


DASS-21 questionnaire
The questionnaire was developed by Lovibond to measure stress, anxiety, and depression and consists of 21 items 39 .The DASS-21 questionnaire consists of 3 subscales of stress, anxiety, and depression, each consisting of 7 items.In this scale, items are measured using a four-items Likert scale (0 = Did not apply to me at all, 1 = Applied to me to some degree, or some of the time, 2 = Applied to me to a considerable degree, or a good part of time, 3 = Applied to me very much, or most of the time).The final score for each subscale is calculated by summing the items.The total score ranges from zero to 63, with lower scores indicating better psychological status.The validity and reliability of this tool were confirmed in a study in Iran and Cronbach's alpha coefficient of stress, depression, and anxiety was reported 0.78, 0.77, and 0.73, respectively 40 .The validity and reliability of the questionnaire was reviewed in this study and the Cronbach's alpha for all questions of DASS and subscales of depression, anxiety, and stress was calculated 0.948, 0.874, 0.854, and 0.853, respectively.

Diabetes health literacy scale
The questionnaire consists of 14 questions and measures three subscales of informational health literacy, numerate health literacy, and communicative health literacy.The questionnaire was designed by Lee, and the validity and reliability of the questionnaire were verified 41 .In Lee's study, Cronbach's alpha of diabetes health literacy and sub-scales of informational health literacy, numerate health literacy, and communicative health literacy were reported 0.90, 0.80, 0.85, and 0.90, respectively 41 .The validity and reliability of this questionnaire was investigated in Iran by Moshki 42 .Cronbach's alpha of total diabetes health literacy scale and sub -scales of numerate health literacy, informational health literacy, and communicative health literacy were 0.919, 0.879, 0.865, and 0.784, respectively.Also, Intra -class correlation of total diabetes health literacy scale and sub -scales of numerate health literacy, informational health literacy, and communicative health literacy were 0.957, 0.921, 0.976, and 0.911, respectively 42 .In this scale, items are measured using a five-items Likert scale (not really = 1 to very much = 5).The total score ranges from 14 to 70, with higher scores indicating better diabetes health literacy status.

Self-care behavior questionnaire
The 10-question examines patients' self-care behaviors over the past 7 days, related the diet, exercise, blood glucose testing, foot care and smoking.The questions in this section were measured using a 5-items Likert scale (too much, much, at all, low, very low).The total score ranges from 10 to 50, with higher scores indicating better Self-care behavior status 43 .The validity and reliability of the questionnaire was reviewed in this study and the Cronbach's alpha for all questions was 0.650.

SWLS
This scale was designed by Diener 44 .This scale consists of five items that measure the well -being status.In this scale, items are measured using a seven-items Likert scale (completely disagree to completely agree).The total score ranges from 5 to 35, with higher scores indicating better life satisfaction.The validity and reliability of the questionnaire was reviewed in this study and the Cronbach's alpha for all questions was 0.927.

QOL questionnaire (SF-12)
The SF-12 questionnaire is a shorter form of SF-36 that survey the QOL and was designed by Ware 45 .This scale consists of 12 questions and 8 subscales of role limitations due to physical problems (RP = 2 items), physical functioning (PF = 2 items), bodily pain (BP = 1 item), general health (GH = 1 item), vitality (VT = 1 item), role limitations due to emotional problems (RE = 2 items), perceived mental health (MH = 2 items), and social functioning (SF = 1 item).These 8 subscales are divided into two components of Mental Health with 6 items (MH, SF, RE, and VT) and Physical Health with 6 items (PF, RP, GH, and BP).The total score ranges from 12 to 47, with higher scores indicating better QOL.The validity and reliability of this questionnaire was investigated in a study in Iran and Cronbach's alpha for components of Mental Health and Physical Health was reported 0.72 and 0.73, respectively 46 .The validity and reliability of the questionnaire was checked in this study and the Cronbach's alpha for all questions of QOL and components of Physical Health and Mental Health was calculated 0.735, 0.762, and 0.60, respectively.

Statistical analysis
In this study, SPSS version 22 software was used to analyze the data.To evaluation the relationship between a quantitative variable and three-categorical or more variables, One-way ANOVA was conducted.To evaluation the relationship between a quantitative variable and two-categorical qualitative variables, Independent-samples t-tests was conducted.Linear regression test was performed to evaluation the role of variables in prediction the QOL.To evaluation the correlation between two quantitative variables, Pearson correlation was conducted.

Ethics approval and consent to participate
This study was based on a research project approved by Ethics Committee of Gonabad University of Medical Sciences with the code of ethics IR.GMU.REC.1400.119.All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable.Written Informed Consent was obtained from all subjects and/or their legal guardian(s) and for illiterate participants.

Results
In the present study, most participants were male (59%) and married (91%).The age of onset of diabetes in most people was over 40 years old, and 37.1% reported that more than 10 years have passed since onset of their diabetes.Other demographic information can be seen in Based on Pearson correlation test results, there was a positive and significant correlation between diabetes health literacy (r = 0.438, p < 0.001), depression (r = − 0.380, p < 0.001), anxiety (r = − 0.355, p < 0.001), stress (r = − 0.423, p < 0.001), and life satisfaction (r = 0.265, p < 0.001) with quality of life.There were negative and significant correlation between diabetes health literacy with depression (r = − 0.372, p < 0.001), anxiety (r = − 0.364, p < 0.001), and stress (r = − 0.370, p < 0.001) (Table 2).Based on the results of linear regression, variables of diabetes health literacy, life satisfaction, self-care behaviors, depression, stress, anxiety, age of onset of diabetes, and diabetes duration were able to predict 31% of QOL (p < 0.001) and diabetes health literacy had the most impact on predicting QOL (p < 0.001) (Table 3).
According to Table 4 results, there was a significant relationship between the age of onset of diabetes with stress (p = 0.033) and anxiety (p = 0.017).There was a significant relationship between diabetes duration with the level of depression, stress, and anxiety (p < 0.001) (Table 4).Based on the results of Table 5, there was a significant relationship between diabetes duration with the level of diabetes health literacy (p < 0.001) and subscales of informational health literacy (p < 0.001), numerate health literacy (p = 0.002), and communicative health literacy (p = 0.003) (Table 5).Based on the results of Table 6, there was a significant relationship between diabetes duration and QOL (p < 0.001).There was also a significant relationship between diabetes duration and the self-care behaviors (p = 0.018) (Table 6).

Discussion
This study is a cross-sectional study was aimed to determine the role of diabetes health literacy, psychological status, self-care behaviors, and life satisfaction in predicting QOL in Iranian patients with type 2 diabetes.The results of this study showed that there was a positive and significant correlation between health literacy and QOL.Also, diabetes health literacy, life satisfaction, self-care behaviors, depression, stress, anxiety, age of onset of diabetes, and duration of diabetes predict 31% of QOL in type 2 diabetes patients and diabetes health literacy has the greatest impact.
The results of this study showed that there was a significant relationship between education status and depression, but this relationship was reversed in our study.This inverse relationship seen in our study may be due to www.nature.com/scientificreports/people's awareness of the disease, and this itself can reduce depression, stress and anxiety in a person.In addition, a person with more knowledge is likely to take better.The study of Sweileh indicated that people who had more education were doing better self -care behavior 47 .The study by Zendegani showed no significant relationship between education status and depression, which may indicated that patients with high education status do not understand the important of self-care behaviors 48 .In our study, may be people with higher education status have more health literacy than diabetes, with increasing education status they experience less depression, stress, and anxiety, but in the previous study, may be this association of education and health literacy has not occurred.In this study, there was a significant relationship between the duration of the disease and depression, and the severity of depression increased with the duration of the disease.These results are consistent with the results of the study of Mosaku et al. 49 , whereas in the study by Zendegani 48 the incidence of depression decreased with increasing duration of diabetes.The increase in depression among patients in this study could be due to persistent self-care behaviors, diabetes burnout, or fear of possible diabetic complications.
The results of this study also showed that there was a relationship between education status and the health literacy of diabetes, which is consistent to the results of other studies [50][51][52] .Usually, with increasing levels of education, people are likely to increase health literacy in different aspects of the disease, which can have a positive effect on self -care behaviors, and this makes them more effective in health follow-up and interaction with their caregivers.to perform better and because of their relative knowledge, they better understand the reason for follow-ups and compliance with treatment orders.As a result, this enables them to conduct health follow-ups and interactions with caregivers more effectively, they better understand the reasons for follow-ups and compliance with treatment orders.
There was a significant relationship between work status and diabetes health literacy, with employed individuals showing higher levels of diabetes health literacy, which is consistent with the findings of Noroozi 50 .This problem may be due to the people interaction with the environment outside the home and with different people, which can improve their health literacy levels.Contrary to the results of this study, results of several studies showed a direct relationship between the duration of diabetes and health literacy 53,54 .It is usually expected with increase duration period of the disease, the level of health literacy and the experiences of diabetes management increase, but in our study, a contradictory result was obtained.It seems that it may be the lack of awareness about the long-term complications of the disease, or another reason may be the decrease in people's sensitivity to the disease and the lack of updating their information by health care providers, which has decreased people's health  literacy with the increase in the duration of diabetes.Therefore, in order to improve the health literacy level of patients, it is necessary to design and implement programs such as education classes for people with low education and older age.According to the results of this study, there was a significant relationship between education status and self-care behaviors, which is consistent with the findings of other studies [55][56][57] .Given that more than 50% of patients in this study had diplomas and higher education, most self-care behaviors were justified.
There was also a significant relationship between the duration of the disease and the self -care behaviors, and with the prolongation of the disease duration, the self-care behavior increases, which was in line with the results of other studies 58,59 .Dietary adherence and better and sustainable relationships with physicians and healthcare providers may be among the reasons for improved self-care behaviors as diabetes duration increases.
The results of this study showed that there was a significant relationship between education status and QOL, and with the increase in the level of education, QOL of patients increased, which was consistent with the results of Glasgow et al. 60 .Higher QOL among patients with increased educational attainment may be due to increased levels of health literacy and better self-care behaviors.
Also, there was a significant relationship between the duration of diabetes and QOL, and with the increased duration of the disease, QOL was reduced in patients, which was consistent with the results of other studies 61,62 .Reducing QOL can be due to numerous complications of diabetes as a result of prolonging the disease.
Stress was also one of the predictors of QOL, and QOL decreased as stress score increased, which is consistent with other studies 12,63 .In the interpretation of this finding, it can be argued that the fear of the problems and consequences of diabetes and the inability to solve these problems can increase stress in patients and thus reduce their QOL.Stress can also lead to lack of dietary adherence, reduced physical activity, and smoking in diabetic, resulting in reduced self-care behaviors and ultimately lower QOL 64 .
Another predictor of patients' QOL in this study was their diabetes health literacy level, meaning that as their health literacy level improved, their QOL improved.Results from similar studies have shown that health literacy is one of the effective factors in improving self-care behaviors, glycemic control (HbA1c) and improving QOL in type 2 patients 65 .Another study found that improving health literacy can increase self-care behaviors and improve QOL in people with diabetes 66 .It seems that health literacy makes people with diabetes pay more attention to self-care, they will be more obedient to the orders of doctors and health care providers, and they are likely to experience fewer complications of the disease; this makes people with type 2 diabetes have a higher QOL.
In this study, life satisfaction was also an effective factor in predicting patients' QOL.With the improvement of life satisfaction, QOL also improved.Given that there was a negative and significant correlation between stress, anxiety and depression with life satisfaction, it seems that reducing these problems can make patients more satisfied and thus increase their QOL.The results of one study showed that patients who are satisfied with the treatment of their illness have a higher QOL 67 .In fact, the more satisfied people are with their lives, the less stress, anxiety, and depression they experience, and ultimately, they can experience a higher QOL.
Finally, the models in our study showed the large impact of diabetes health literacy on QOL.Health literacy appears to be effective for all psychological factors in people with diabetes, and improving health literacy in these www.nature.com/scientificreports/patients can reduce their depression, anxiety and stress and improve their QOL.Informing type 2 diabetes about their disease in such a way that they know their disease and know its complications and eventually leads to people's compliance with the treatment staff 's orders can provide a better health status and a higher QOL for patients.

Conclusion
The results of this study showed that diabetes health literacy, life satisfaction, stress and duration of diabetes can predict QOL of diabetic, and our study highlights the impact of health literacy on QOL in diabetic.Therefore, it is necessary to pay more attention to these effective variables when planning educational programs and design appropriate programs for this field.In fact, by increasing diabetes health literacy of type 2 diabetic, we can maintain and improve their QOL, because increasing diabetes health literacy level of people makes the patients aware of their disease, act more committed to medical orders, and have more self-care, and finally, they will suffer less stress, anxiety, or depression.In fact, these mental complications can cause patients to fall into a vicious circle.The more stress, anxiety, and depression a person has, the worse the diabetes will be, and the worse the mental state will be.Therefore, increasing the level of health literacy can reduce many of these cases and provide a better quality of life for patients. https://doi.org/10.1038/s41598-024-51245-xwww.nature.com/scientificreports/

Table 1 .
Characteristics of demographic variables.

Table 3 .
The results of linear regression analysis in predicting quality of life.

Table 4 .
Relationship between demographic variables and psychological status (depression, stress, anxiety).
a Independents sample T-test, b One-way ANOVA.

Table 5 .
Relationship between demographic variables and diabetes health literacy.

Table 6 .
Relationship between demographic variables with Self-Care, SWLS, and quality of life.a Independents sample T-test, b One-way ANOVA, c Satisfaction with Life Scale (SWLS).